About 40.1 million people in the United States have diabetes, which works out to roughly 1 in every 8 Americans. That number includes both people who know they have it and a surprisingly large group who don’t: more than 1 in 4 adults with diabetes have never been diagnosed. Beyond that, another 115.2 million adults have prediabetes, a condition where blood sugar is elevated but not yet high enough to qualify as diabetes.
Diagnosed vs. Undiagnosed Diabetes
Of the 40.1 million total, about 29.1 million have received a formal diagnosis. The remaining cases, roughly 11 million people, are walking around with diabetes and don’t know it. CDC survey data from 2021 to 2023 puts the undiagnosed rate at 4.5% of all U.S. adults, compared to 11.3% who have been diagnosed. Men are more likely to have undiagnosed diabetes than women (4.9% vs. 3.5% after adjusting for age).
Undiagnosed diabetes is identified through national health surveys where participants give blood samples. If their fasting blood sugar or long-term blood sugar marker comes back in the diabetic range but they report never receiving a diagnosis, they’re counted in the undiagnosed group. These aren’t mild or borderline cases. They meet the same lab thresholds used to diagnose diabetes in a clinic.
Type 1 vs. Type 2 Breakdown
The vast majority of diabetes in the U.S. is Type 2. Among all diagnosed cases, about 91% are Type 2 and roughly 6% are Type 1, with the remaining 3% classified as other types (including gestational diabetes and rarer forms). In raw numbers, an estimated 2.1 million Americans have diagnosed Type 1 diabetes, including about 314,000 children and adolescents under 20. Type 2 accounts for the overwhelming bulk of the 29.1 million diagnosed cases.
Type 1 is an autoimmune condition where the body destroys the cells that produce insulin. It typically appears in childhood or young adulthood and requires lifelong insulin. Type 2 develops when the body becomes resistant to insulin or stops making enough of it, and it’s closely tied to weight, activity level, age, and genetics.
Prediabetes: The Larger Hidden Problem
The 40.1 million figure only captures full diabetes. Prediabetes affects more than twice as many people: 115.2 million U.S. adults, or more than 2 in 5. Among adults 65 and older, 31.3 million (52.1%) have prediabetes. And 8 in 10 people with prediabetes don’t know they have it.
Prediabetes means your blood sugar is higher than normal but hasn’t crossed the diabetes threshold. Without changes to diet, exercise, or weight, a significant portion of people with prediabetes will develop Type 2 diabetes within several years. The condition produces no obvious symptoms, which is why awareness is so low despite how common it is.
Where Diabetes Rates Are Highest and Lowest
Diabetes prevalence varies dramatically by state. The national median for diagnosed diabetes among adults is 10.3%. The states with the highest rates cluster in the Southeast:
- West Virginia: 15.0%
- Mississippi: 14.7%
- Louisiana: 14.5%
- Alabama: 13.7%
The lowest rates are found in northern and western states:
- Vermont: 7.7%
- New Hampshire: 7.9%
- Montana: 7.9%
- Colorado: 8.0%
- Utah: 8.0%
These gaps reflect differences in obesity rates, poverty, access to healthcare, diet patterns, and physical activity levels. The difference between the highest and lowest states is nearly double.
The Economic Cost
Diabetes costs the U.S. an estimated $412.9 billion per year. Of that, $306.6 billion goes to direct medical costs, things like medications, hospital visits, and ongoing care. The remaining $106.3 billion comes from lost productivity: reduced performance at work ($35.8 billion), missed workdays ($5.4 billion), chronic disability, and premature death. National healthcare spending on diabetes rose by $80 billion over the past decade, from $227 billion in 2012 to $307 billion in 2022.
People with diagnosed diabetes spend roughly 2.6 times more on medical care than they would without the condition. Much of that spending goes toward managing complications like kidney disease, nerve damage, and cardiovascular problems, which are among the most expensive conditions to treat long-term.
Putting the Numbers Together
When you add up everyone affected, the scale is staggering. About 40 million Americans have diabetes (diagnosed and undiagnosed), and another 115 million have prediabetes. That means roughly 155 million people in the U.S., close to half of all adults, have some form of abnormal blood sugar. The condition is most concentrated among older adults and in the southeastern United States, but no demographic or region is unaffected.